Circuit interrupter for infinitely variable electric switches



Apnl 4, 1950 w. R. TUTTLE 2,503,082

cmcurr INTERRUPTER Foa IN1-rumeur VARIABLE ELECTRIC swncmss med oct. 1o. 194s Paten-ted Apr. 4, 1950 CIRCUIT INTEBRUPTEB FOB. INFINITELY VARIABLE ELECTRIC SWITCHES William B. Tuttle, Riverside, Ill., signor to Tuttle Kilt, Inc., Chicago, Ill., a corporation of Illinois Application October 10, 1946, Serial No. 702,405

(Cl. 20o-33) 4 Claims. l

My invention relates to electric current controllers of the type shown in Patent No. 2,294,573, granted September 1, 1942, to Paul H. Potter wherein the amount of current supplied is regulated by intermittently interrupting the circuit and varying the duration or frequency of the interruption, and has reference more particularly to improved circuit interrupting mechanism.

Intermittently interruptible circuit controllers of the character to which this invention relates are particularly desirable for regulating the current supply to electrical heating devices, such as the surface units of electric ranges, so as to afford infinite variations of current supply whereby any desired rate of heating or cooking is available from the lowest extreme to full heating capacity of the particular unit.

In such controllers, it is necessary that the timing of the open circuit and closed circuit periods be accurately controlled throughout the range of adjustment in order to insure progressive variations in current supply according to the adjustment of the control knob or according to the calibrations which represent the heating rate for which the control knob is adjusted.

However, as the cycling period of such controllers, that is, the combined open and closed circuit period, is usually of rather long duration, for example approximately one minute, and the opening and closing of the circuit contacts is correspondingly slow, it is quite diillcult to insure accurate timing, especially with the usual leaf spring supported contacts which it is desirable to employ in such controllers. Any inaccuracies in the engagement and disengagement of the contacts is likely to have a prolonged effect greatly impairing the precision and serviceability of the device.

For example, if either contact is tilted so that it does not engage flatwise against the other contact throughout the range of infinite adjustment of the control, it will cause considerable inaccuracy in the timing because of premature engagement and delayed disengagement, particularly in view of the slow rate of the engaging and disengaging movement of the contacts. Moreover, excessive heating of the contacts is likely to occur owing to the slowness in reaching full flat contact and in this slow progress from tilting contact to final full flat contact (and vice versa) there is likely to be a rubbing action which may cause objectionable radio interference.

Furthermore, as the variations in the heating or cooking rate are accomplished in these controllers by adjustment which shifts the location 1 2 at which the contacts engage and disengage, it is necessary that ilatwise engagement and disengagement of the contacts be maintained irrespective of the shifting of such engagement and disengagement location and that there shall be no rubbing action of one contact against the other either in the engaging or disengaging thereof or in the shifting of the location where such engagement and disengagement occurs.

'I'he principal objects of my invention are to provide an improved multiple circuit controller of the above-mentioned type; to insure accurate timing thereof; to maintain the contacts in ilatwise engageable relation throughout the range of adjustment of the controller; to avoid inaccuracies of control that might cause radio interference; and to eliminate the diillculties heretofore encountered with leaf spring supported contact; these and other objects being accomplished as pointed out more fully hereinafter and as shown in the accompanying drawing in which:

Fig. 1 is a top plan view of a circuit interrupting unit of a multiple circuit controller, with the cover and control knob removed;

Fig. 2 is an enlarged sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a view of the upper end of the eccentric pin of Fig. 2;

Fig. 4 is an enlarged sectional view on the line 4 4 of Fig. 1; and

Fig. 5 is an enlarged sectional view on the line 5 5 of Fig. 1.

Controllers of the character to which this invention relates are particularly adapted to control surface units of electric ranges and as each surface unit is individually controlled, a separate circuit interrupter mechanism is required for each surface unit.

These interruptor mechanisms are motor operated and it is customary to employ a single motor and arrange the separate circuitinterrupter mechanisms around a motor operated member, as shown in the aforesaid Potter Patent No. 2,294,573, so that said member serves as a common actuator for all the interrupter mechanisms.

Electric ranges usually have four surface units and accordingly the controllers therefor, as shown in said Potter patent, have four separate circuit interrupter mechanisms preferably located respectively in the four corners of a case or housing at the center of which is the motor driven common actuator by which the four interrupter mechanisms are operated, each interrupter mechanism, however, being individually adjustable by a knob to regulate the supply of current to the particua,sos,osa

3 lar surface unit which it controls so as to furnish any rate of heating from the lowest extreme to the maximum heating capacity of the particulai unit. and to turn off the surface unit when it is not in use.

In the accompanying drawing wherein Fig. 1 shows one of the circuit interrupter mechanisms of such multiple unit controller, the reference numeral III indicates one corner portion of the ment of the switch member 25, thereby intermittently supplying current to the heating unit for periods of selectible duration whereby the heating unit may be energized to heat at any de- 5 sired rate between "olf" and full on.

case or housing of the multiple unit controller,

which said case or housing has a bottom II and a surrounding side wall I2. A removable cover I3, which is omitted from Fig. 1, is secured to the case by bolts (not shown) extending through openings I4 in corner iillers I5 of the case or 15 housing. The case or housing and the cover I3 are preferably of insulating material so that the various electrical conductors attached thereto are thereby electrically insulated from one another.

Centrally located in the case or housing is a cam I6 secured on a shaft I1 which is operated by a motor 45, at a slow constant rate of speed, such as one revolution per minute.

Each circuit interrupter unit of the multiple circuit controller has a switch member I8 which bears upon the periphery of the cam I6 and is composed of a leaf spring I9 secured at one end to a mounting bracket 20 which is in turn secured to the bottom wall II of the housing. At

the other end of said leaf spring I9 a contact member 2| is secured thereto.

This leaf spring I9 is formed with a bend 22 adjacent the mounted end and beyond this bend is reinforced by a stiffener bar 23 which extends 35 beyond the free end of the leaf spring I9 and has an offset outer end portion 24 which bears against the cam I 6.

Thus the exing of the spring I9 is localized at the bend 22 and there is no exing of the 40 switch member I8 therebeyond.

A companion switch member comprising a leaf spring 25 is secured at one end to a mounting bracket 26 on the bottom wall II of the housing and extends in spaced apart relation to the leaf spring I9 to a location opposite the outer end of the latter spring and at its outer end has a. contact 21 -thereon opposite and engageable against the contact 2I of the leaf spring I9. This leaf spring 25 also has a bend 28 adjacent its 50 mounting bracket 26.

This switch member I8 is biased to have a tendency to bear constantly on the cam I6 and the switch member 25 is likewise biased to have a tendency to separate from the switch member I8, the switch member 25 being adjustable from a position just out of reach of the switch member I8 to a position in which it holds the switch arm I8 just out of reach of the cam I 5.

This switch I8, 25 controls the supply of cur- C0 rent to the resistance 29 of the heating unit and when the switch member 25 is adjusted to the position out of reach of the switch member I8 the switch is in the off position and n0 current is supplied to the heating unit whereas G5 for a length oi' time varying with the adjust- 75 For adjusting the switch member 25 an operating lever 30 is provided which is pivoted at one end near the mounted end of the switch member 25 as indicated at 3| and has the opposite e'nd laterally offset as at 32 to engage against the free end of the leaf spring 25 substantially beyond the center of the contact 21, as shown in Fig. 1, and a cam 33 engages peripherally against this operating lever 38 substantially midway between the ends thereof and is shaped so that in the rotation thereof it swings the lever 30 and the switch member 25 from the olf position to the full on position.

This cam 33 is fixed on a stem 434 which is journaled in the housing bottom Wall II and in the cover I3 and has one end projecting through the cover and provided with an operating knob 35 by which the cam is adjusted.

The cam 33, as shown in Fig. 1, has a fiat peripheral face portion 35 against which the lever 30 lies fiatwise in the off position of the switch and from one end of the fiat face 36 there is a gradual rise radially in the cam surface peripherally therearound to a high projection 31 at the other end of said fiat face 36 which said projection 31, when engaged with the lever 30 maintains the switch member 25 in a position in which it holds the switch member I8 just beyond reach of the cam I6.

With this construction and arrangement of the switch members I8 and 25 the pivoting of the member I8 is localized at the bend 22 and there is no distortional flexing of the leaf spring I9 which is likely to contribute error in timing or interfere with fiatwise engagement of the contact 2I with the mating contact 21 and likewise the adjustment of the switch member 25 by the rigid operating lever 30 through its engagement with the leaf spring 25 beyond the center of the contact 21 causes this contact, in

lthe various positions of adjustment of the switch member 25, to assume the proper position for atwise engagement of the contact 2| therewith, and a high degree of accuracy of timing is insured without any lateral relative movement of the engaged contacts which would cause radio interference. y

Some adjustment is desirable to compensate for slight inaccuracies in manufacture of the parts or to compensate for wear and thus insure precise correspondence with the knob adjustment or the calibrations which indicate the rate of heating for which the knob is adjusted and for this purpose the operating lever is mounted at its pivoted end in a manner to permit a slight degree of adjustment of the pivotal center.

To this end the lever is pivoted on an eccentric portion 38 of a pin 39 which has an enlarged elongated head snugly engaged in an opening through a locally thickened portion of the bottom wall I I of the case or housing and which, at its upper end, has a bearing terminal 40 engaged in a seat 4I on the underside of the cover I3, the eccentric portion 38 being about ten one-thousands oi center so that by engaging the slotted outer end of the head of the pin with a screw-'driver and turning the pin, a ne adjustment of the pivotal center to and from the leaf spring 25 may be made. This adjustment changes the relation of the center portion of the lever 30 sumciently with the surface of the cam 33 to accomplish a fine adjustment of the timing.

After the pin 39 has been accurately adjusted the end of the pin opening may be filled with sealing wax 42 to permanently retain the pin 39 in the adjusted position. Preferably a washer 43 is interposed between the shoulder and offset between the head of the pin 39 and the eccentric portion 38 to support the pivot end of the lever as shown in Fig. 2.

Co-axial with the regulator cam 33 is an auxiliary cam 44 which rotates in unison with the cam 33 and serves the dual purpose of completing the heating element circuit and the circuit to the motor 45 which operates cam I6. The said auxiliary cam 44 bears against a U-shaped hump 46 of the leaf spring 41. Said spring 41 is mounted at one end on a metal bracket 48 and is provided at its opposite end with an elongated contact 49. Cooperating therewith are two contacts 50 and 5|. 52 and 53, respectively, which are in turn mounted upon metal brackets 55 and 55.

When the regulator cam 33 is in the position illustrated in Fig. 1, so that the contact 21 is fully retracted to the "oiT position, the auxiliary cam 44 is disposed so that the convexity 46 of the spring strip 41 is received in the concavity 51 on the peripheral edge of said cam 44. In this position, the elongated contact 49 is held by the tension of spring strip 41 out of engagement with the co-operating contacts 50 and 5| As the regulator cam 33 is turned in a clockwise direction to the point where the contact 21 is held in its fully extended or full on position, the auxiliary cam 44 advances therewith to a position where the hump 46 of the spring strip 41 is engaged between two humps 58 on the peripheral edge of the auxiliary cam 44. These humps 58 serve to center lthe respective cams 33 and 44 in the full on position. In this position, the elongated contact 49 is extended into engagement with contacts 50 and 5|. As the turning of the said cams is continued in a clockwise direction, the cam 44 continues to hold the elongated contact 49 in engagement with the contacts 50 and 5|.

The contact 50 is connected through leaf spring 52, bracket 55 and conductor 59 to the electrical source designated by the plus symbol and when the elongated contact 49 is extended into engagement therewith, said side of the line is connected through said contact 49, leaf spring 41, bracket 48 and conductor 6| to one end of the resistance 29, the other end of which is connected through conductor 62 intermittent switch I8, 25 and conductor 54 to the side of the line. Contact 5| is engaged at the same time as contact 50 by the extension of elongated contact 49. Electric current is thus Supplied from the side of the line through contact 5|, leaf spring 53, bracket 56 and conductor 50 to one terminal of the motor 45, the other terminal of which is connected by the conductor 63 to the side of the line. Thus, the cam l5 is placed in operation by turning on the switch for any of the units in the multiple circuit controller.

Completion of the heating unit circuit is dependent upon engagement of the contacts 2| and 21, as will be seen in Fig. 1, and the intensity of the heat developed in the heating unit will be determined by the duration of the engagement between said contacts 2| and 21 during each cycle of the cam I6 and the duration of this engagement depends upon the position in which the switch member 25 is held by engagement of supported upon springy strips the operating lever 30 with the peripheral surface of the cam 33.

While I have shown and described my invention in a preferred form, I am aware that various changes and modifications may be made therein without departing from the principles of my invention, the scope of which is to be determined by the appended claims.

What I claim is:

1. In an intermittently operable switch of the class described, the combination of a pair of proximately mounted spring arms which extend in laterally spaced side by side relation from the place of mounting and are biased in the same direction and electrically insulated from one another, each spring arm having at its free end a contact which faces toward and is engageable with the contact of the other spring arm to close an electrical circuit through the spring arms and the contacts. and a separate actuator for each spring arm by which the respective spring arm is individually displaceable in the direction in which it is biased as aforesaid, a rigid member which extends alongside one of said spring arms in laterally spaced relation thereto and is pivoted near the mounted end of said arm and bears against the free end of said arm, one of said actuators being manually operable and engaged against said rigid member to adjust the contact of the last mentioned spring arm selectively toward and away from the contact of the other spring arm, and the other actuator being engaged with said last mentioned spring arm at the outer end thereof and constantly operable to engage the contact of the latter arm intermittently with the contact of the other arm for successive periods of time, the duration of which is determined by the adjustment of the manually operable actuator.

2. In an intermittently operable switch of the class described, the combination of a pair of proximately mounted spring arms which extend in laterally spaced side by side relation from the place of mounting and are biased in the same direction and electrically insulated from one another, each spring arm having at its free end a contact which faces toward and is engageable with the contact of the other spring arm to close an electrical circuit through the spring arms and the contacts, and a separate actuator for each spring arm by which the respective spring arm is individually displaceable in the direction in which it is biased as aforesaid, a rigid member which extends alongside one of said spring arms in laterally spaced relation thereto and is pivoted near the mounted end of said arm and bears against the free end of said arm, directly behind the contact of that arm, one of said actuators being manually operable and engaged against said rigid member to adjust the contact of the last mentioned spring arm selectively toward and away from the contact of the other spring arm, and the other actuator being engaged with said last mentioned spring arm at the outer end thereof and constantly operable to engage the contact of the latter arm intermittently with the contact of the other arm for successive periods of time, the duration of which is determined by the adjustment of the manually operable actuator.

3. In an intermittently operable switch of the class described, the combination of a pair of proximately mounted spring arms which extend in laterally spaced side by side relation from the place of mounting and are biased in the same di- 7 rection and electrically insulated from one another, both spring arms being correspondingly bent at their mounted ends and each spring arm having at its free end a contact which faces toward and is engageable with the contact of the other spring arm to close an electrical circuit through the spring arms and the contacts, and a separate actuator foreach spring arm by which the respective spring arm is individually displaceable in the direction in which it is biased as aforesaid. a rigid member which extends alongside one oi' said spring arms in laterally spaced relation thereto and is pivoted near the mounted end oi said arm and bears against the free end of said arm, one of said actuators being manually operable and engaged against said rigid member to adjust the contact of the last mentioned spring arm selectively toward and away from the contact of the other spring arm, and the other actuator being engaged with said last mentioned spring arm at the outer end thereof and constantly operable to engage the contact of the latter arm intermittently with the contact of the other arm for successive periods of time, the duration' of which is determined by the adjustment of the manually operable actuator.

4. In an intermittently operable switch of the class described, the combination of a pair of proximately mounted spring arms which extend in laterally spaced side by side relation from the place of mounting and are biased in the same direction and electrically insulated from one another, each spring arm having at its tree end a contact which faces toward and is engageable with the contact of the other spring arm to close an electrical circuit through the spring arms and the contacts, and a separate actuator -for each spring arm by which the respective spring arm 8 is individually displaceable in the direction in which it is biased as aforesaid, a rigid member which extends alongside one of said spring arms in laterally spaced relation thereto and is -pivoted near the mounted end of said arm and bears against the free end of said arm, one of said actuators being manually operable and engaged against said rigid member to adjust the contact of the last mentioned spring arm selectively toward and away from the contact of the other spring arm, and the other actuator being engaged with said last mentioned spring arm at the outer end thereof and constantly operable to engage the contact of the latter arm intermittently with the contact of the other arm for successive periods of time, the duration oi which is determined by the adjustment of the manually operable actuator, said rigid member being eccentrically mounted at its pivoted end on a rotatable pivot and said pivoted end being adjustable by rotation of said rotatable pivot to and from the mounted end of the spring arm alongside of which the pivoted arm extends.

WILLIAM R. TU'I'I'LE.

REFERENCES CITED The'following references are of record in the ille of this Ipatent:

UNITED STATES PATENTS 

